This invention relates to a system for automatically locking the doors of a motor vehicle equipped with electric power door locks, and more particularly, to an automatic door locking system, which provides one mode of operation for vehicles equipped with automatic transmissions and a second mode of operation for vehicles equipped with manual transmissions.
Conventional electric power locks have been used extensively in automobiles, to provide a convenient way for locking and unlocking vehicle doors. Typically, each door is provided with a door latching mechanism, which is mechanically linked to an electrically reversible locking motor. A centralized relay assembly having separate locking and unlocking relay coils is used to appropriately actuate the electric motors to drive the latching mechanisms to lock or unlock the vehicle doors. The relay coils are remotely energized by door lock switches located near the vehicle driver and passengers.
When a vehicle is furnished with electric power locks, it is desirable to provide a means for automatically locking the vehicle doors, at least initially after starting the vehicle engine, to aid the vehicle occupants, who may have forgotten to do so. This prevents unauthorized door openings, for example, when the vehicle is stopped at a traffic signal.
In the past, systems have been provided for automatically locking the doors, when a vehicle is driven above a predetermined speed. This type of system functions satisfactorily for vehicles equipped with manual and automatic type transmissions; however, when possible, it has been found desirable to base automatic door locking on a more direct driver input. To this end, vehicles equipped with automatic transmissions have been furnished with systems that automatically lock the doors, whenever the transmission is shifted from park to a different range, as indicated by a transmission shift selection switch. Although this mode of automatic door locking is preferable, it is not readily applicable to vehicles having manual transmissions, since these vehicles may be started with the transmission in any gear, and a shift selection switch is normally not provided.
Consequently, a primary disadvantage associated with these prior systems is that vehicles equipped with automatic transmissions require automatic locking systems, which differ from those of vehicles having manual transmissions, when the more preferred mode of automatic door locking is to be used with each type of transmission.